Mobile or portable user terminals may operate on a narrowband system, for example, a Land Mobile Radio (LMR) system. These mobile or portable user terminals include mobile radios, portable radios or other similar voice communication entities that communicate with one another via wired and/or wireless networks. The mobile or portable user terminals (collectively referred to as radios) may operate in areas where there is inconsistent coverage or in areas where there are dead spots (i.e., no coverage) in specific locations. For example, radios that are otherwise operable in a building may be inoperable in the basement of the building with concrete floors because the concrete floors may block or restrict radio frequency (RF) signals being transmitted to or from the radios. In another example, the radios that are otherwise operable in a restaurant may be inoperable in a metal stockroom or storage cage in a kitchen of the restaurant because the metal may block the RF signals being transmitted to and from the radios.
In addition, the radios may operate on different portions of an RF spectrum, wherein certain licensed portions of the RF spectrum may be subject to increased interference. When there is interference on a frequency being used by a sending radio that is operating in a repeater system (i.e., a system where a signal is sent from the sending radio to a repeater and then forwarded from the repeater to one or more receiving radios), the sending radio is typically unable to switch to another frequency with less interference because a duplexer in the repeater is typically tuned at a manufacturing site to a fixed frequency for sending signals from the repeater and to another fixed frequency for receiving signals at the repeater. Therefore, there is a need for a frequency agile system where the radios can be dynamically configured to communicate on different frequencies. In addition, although the duplexer enables the repeater to simultaneously receive and transmit signals, duplexers are relatively bulky and costly devices.
Furthermore, the radios used by public safety agencies, for example, emergency first responder organizations such as police or fire departments, or public works organizations, may operate according to different proprietary protocols or may operate on different RF bands. For example, a police department may operate according to a first proprietary protocol and a fire department may operate according to a second proprietary protocol. Using this example, when an incident, such as a fire, accident or other public safety emergency occurs, the radios operating on the first protocol may be unable to communicate with the radios operating on the second protocol. In addition, radios used in a first communication system operating on a first RF band may be unable to communicate with radios used in a second communication system operating on a second RF band. For example, the radios in a firefighter communication system may operate in the Very High Frequency (VHF) band and radios in a medical communication system may operate in the Ultra High Frequency (UHF) band. Therefore, the radios in the firefighter communication system may be unable to communicate with the radios in the medical communication system.
Accordingly, there is a need for an improved method and apparatus for enabling radios to communicate, regardless of the protocol or the band on which the radios operate, and thereby extend coverage in a wireless communication system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.